VOLUMETRIC MEASUREMENT OF BRAIN-TUMORS FROM MR-IMAGING

Residual tumor volume has been considered important in predicting surv ival following brain surgery. The purpose of this study was to develop a procedure for quantifying pre-and postsurgical brain tumor volumes that is less subjective than the traditional qualitative grading scale still used by surgeons and radiologists to assess extent of resection (such as gross total, subtotal, and partial resection). Pre-and posts urgical magnetic resonance (MR) imaging brain scans on GE Medical Syst em optical disks were transferred to a Macintosh personal computer usi ng a Pioneer optical disk drive subsystem, and the MedVision 1.41 comp uter software program was used to analyze regions of interest (ROIs) w ithin them for computation of the volume of tumor tissue therein. Beca use this procedure puts the original MRI (or CT scan) data file for a patient directly into the personal computer, it bypasses the need for scanning and digitizing MR (or CT scan) film images. Between June 1993 and May 1996, pre-and postsurgical volumetric measurements were made in more than 1,000 brain tumor resection cases and 49 radiosurgery cas es. The average intra-observer error was estimated to be 1.8%. This me thod should facilitate the examination of the effects of various thera pies on extent of brain tumor resection. The method is fast, is more p recise than intraoperative visual assessment of tumor removal or quali tative comparison of pre-and postoperative scans, and it allows the co mputation of pre- and postsurgical (three-dimensional) volumes of even irregularly shaped tumors.